Implementing Kubernetes Jobs with NestJS and nest-commander: A Practical Guide (Ex. implementation with Ticketmaster)

Hey there! Ever found yourself knee-deep in building NestJS applications and thought, “Man, I wish I could bring this awesome structure to my command-line tools”? Well, you’re in luck! The nest-commander package does just that, letting you craft CLI applications with the same NestJS flair you know and love.

But wait, there’s more! Imagine taking these slick CLI apps and running them as jobs in a Kubernetes environment. Sounds like a dream, right? That’s where the nestjs-job-commander repository comes into play. It’s a nifty example showing how to set up a job processing system using NestJS and nest-commander, all within Kubernetes.

In this article, we’ll explore the details of this setup, breaking down the implementation so you can try it out yourself. Let’s get started!

https://github.com/henriqueweiand/nestjs-job-commander

Technologies used 🛠️

• NestJS: A progressive Node.js framework for building efficient and scalable server-side applications.
• nest-commander: A NestJS module that facilitates the creation of CLI applications with a structure similar to typical NestJS applications. Find out more about it https://docs.nestjs.com/recipes/nest-commander
• TypeORM: An ORM for TypeScript and JavaScript that supports various databases. Find out more about it https://docs.nestjs.com/recipes/sql-typeorm
• Kubernetes (k8s): An open-source system for automating deployment, scaling, and management of containerized applications.
• Monorepo: A repository structure that holds multiple projects, allowing for shared code and unified project management. Find out more about it https://docs.nestjs.com/cli/monorepo

Repository Structure 🗺️

The repository is organized as a monorepo, containing multiple projects and shared libraries. Key components include:

• apps/cli-enricher: The CLI application is built with NestJS and nest-commander.
• libs: Shared libraries utilized by the CLI application.
• k8s: Kubernetes configuration files for deploying the job.
• Dockerfile: Defines the Docker image for the CLI application.
• .env: Environment variables configuration file.

In this repository, we will get into just one CLI, but you can have as many as you need.

CLI Enricher

Similar to a traditional NestJS application, an application with NestJS Commander is set up quite simply. In the main.ts we define the bootstrap method

https://github.com/henriqueweiand/nestjs-job-commander/blob/master/apps/cli-enricher/src/main.ts

Then, we need to create the AppModule, which will require the base modules like ENV Module, Database connection, and also the module for your CLI, in this case, I just have one, but, if you have more, don't forget to add them here!

https://github.com/henriqueweiand/nestjs-job-commander/blob/master/apps/cli-enricher/src/app.module.ts

The AppModule needs to export the main command, that's why there's an export. Opening the CliCommand, you will notice a base structure for a general CLI command, and the reason it is quite basic is that this project is not using the root command, it is using subCommands. There's no big reason for that, I decided to use it as a subcommand instead of a root, but I will detail more about it later.

https://github.com/henriqueweiand/nestjs-job-commander/blob/master/apps/cli-enricher/src/cli-command.ts

I'm going to explain more about how to use the root command at the end of the article, for now, let's stick to the app context.

Yet inside the CliCommand, we need to define the subCommands, and then it is necessary to add the command file of that.

https://github.com/henriqueweiand/nestjs-job-commander/blob/master/apps/cli-enricher/src/cli-command.ts

This is the core of our CLI Enricher. In this file, we define the command name

@SubCommand({ name: 'ticketmaster-event-refresh' })

TicketMasterEventRefreshCommand holds the logic of our CLI Job. The job gets the events from the Ticket Master API, verifies whether the event exists or not, and stores it. Again, the logic is not the focus of the post, but how to manage Nest Commander inside the Kubernetes.

https://github.com/henriqueweiand/nestjs-job-commander/blob/master/apps/cli-enricher/src/ticketmaster-event-refresh/ticketmaster_event_refresh.command.ts

By using subCommands, in the end, we will execute it like this

-- cli ticketmaster-event-refresh

Running the job - outside k8s

In case you need to test the application before putting it inside the k8s, which I strongly recommend. You can do that by running the command

nest start --watch -- cli ticketmaster-event-refresh

⚠️ Make sure you have everything that your application needs to run ready, for example, the database instance and the tables.

This project has a how-to-run section in the README file to help you to run this example locally without any issues.

Running the job - inside k8s

So far, we have a NestJS application with NestJS Commander, and we know that the application works! The next step is putting the app inside a Pod in the k8s, and for that, we will need to create two things!

1. The docker image;
2. Kubeclt file for the cronjob;

For the docker image, we only need to run

docker build -t ticketmaster-event-refresh-job .

The command will build the Dockerfile available at the root level, and this Dockerfile doesn't have anything different from any other NestJS application with docker, but, feel free to take a look.

Next, change the .env file and add the following envs

CLI-ENRICHER.HOST=host.docker.internal
NODE_ENV=production

Since we are going to run the app inside the cluster, we need to set the correct host to make it able to reach the database. The NODE_ENV with the production value is required because of the logic for the EnvModule.

Now, create a config map inside your cluster. Run the command

kubectl create configmap env-config --from-env-file=.env

This command will create a config map and add the .env variables inside it. We will need the .env to run the application inside the cluster.

The last step is running the kubeclt command. Go to the k8s folder and execute

kubectl apply -f cronjob.yaml

In case you want to know, the cronjob.yaml is a spec file to create a job inside the k8s.

https://github.com/henriqueweiand/nestjs-job-commander/blob/master/k8s/cronjob.yaml

The job is being set to run each minute, and it follows the same sequence of commands as we tested outside the k8s previously.

command:
  - node
  - dist/apps/cli-enricher/main.js
  - cli
  - ticketmaster-event-refresh

I recorded a video to help you to run everything in case is needed!

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Conclusion

And there you have it! With NestJS Commander and Kubernetes, you can seamlessly build and deploy CLI applications using the familiar NestJS structure. This setup allows you to manage jobs efficiently, whether running them locally or within a Kubernetes cluster.

By leveraging subCommands, Docker, and Kubernetes CronJobs, we’ve created a system that can scale and automate job execution while maintaining flexibility. If you’re working on task automation, scheduled jobs, or batch processing, this approach can help you streamline your workflow.

I mentioned earlier that I’d dive deeper into root commands and parameter handling—don’t worry, that’s coming in a future post! Stay tuned, and in the meantime, feel free to check out the nestjs-job-commander repository and try it yourself.

Got questions or feedback? Drop a comment or reach out—I’d love to hear your thoughts! 🚀